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Abstract:

A pilot addition method and a pilot addition apparatus. The pilot
addition method is used in a transmitter for transmitting data to
subscriber of an old system and subscriber of a new system serving as an
updated system of the old system, including: judging whether or not to
insert a pilot required by the subscriber of the new system into a
current resource block, determining a sub-carrier symbol block serving as
an insertion position of the pilot required by the subscriber of the new
system, from one or more sub-carrier symbol blocks having a large
influence on the statistical performance of a channel estimation for the
subscriber of the old system; and inserting the pilot required by the
subscriber of the new system into the sub-carrier symbol block serving as
the insertion position of the pilot required by subscriber of a new
system. determined by the determining.

Claims:

1. A pilot addition method used in a transmitter for transmitting data to
subscriber of an old system and subscriber of a new system serving as an
updated system of the old system, comprising: judging whether or not to
insert a pilot required by the subscriber of the new system into a
current resource block, determining a sub-carrier symbol block serving as
an insertion position of the pilot required by the subscriber of the new
system, from one or more sub-carrier symbol blocks having a large
influence on the statistical performance of a channel estimation for the
subscriber of the old system; and inserting the pilot required by the
subscriber of the new system into the sub-carrier symbol block serving as
the insertion position of the pilot required by the subscriber of the new
system determined by the determining.

2. The pilot addition method according to claim 1, wherein the
determining determines the insertion position of the pilot required by
the subscriber of the new system according to a sector.

3. The pilot addition method according to claim 2, wherein in case a
pilot of an antenna of the new system is located at a sub-carrier having
a serial number k in a certain source block in the first sector, a
sub-carrier for the pilot of the antenna in corresponding source block in
the second sector has a serial number of k+1 modulo k, and a sub-carrier
for the pilot of the antenna in corresponding source block in the third
sector has a serial number of k+2 modulo k, k is a nonnegative integer.

4. The pilot addition method according to claim 1, wherein the old system
is an LTE system and the new system is an LTE-A system.

5. The pilot addition method according to claim 4, wherein the judging
determines inserting the pilot required by the subscriber of the new
system into each or several of resource blocks in 0.sup.th to 3.sup.rd
sub-frames, 6.sup.th to 9.sup.th sub-frames, or 2.sup.nd to 9.sup.th
sub-frames, or 1.sup.st to 4.sup.th sub-frames and 6.sup.th to 9.sup.th
sub-frames of the frame.

6. The pilot addition method according to claim 4, wherein the judging
determines inserting the pilot required by the subscriber of the new
system into each of resource blocks in a 2.sup.nd sub-frame, a 3.sup.rd
sub-frame, a 7.sup.th sub-frame and an 8.sup.th sub-frame of the frame.

7. The pilot addition method according to claim 4, wherein the judging
determines inserting the pilot required by the subscriber of the new
system into each of resource blocks in any one or two of a 2.sup.nd
sub-frame, a 3.sup.rd sub-frame, a 7.sup.th sub-frame and an 8.sup.th
sub-frame of the frame.

8. The pilot addition method according to claim 5, wherein the
determining determines insertion positions of pilots of four antennas in
each of resource blocks such that pilots added to resource blocks with
the same serial number in adjacent sub-frames are for different antennas.

9. The pilot addition method according to claim 5, wherein the
determining determines insertion positions of pilots of four antennas in
each of resource blocks such that pilots added to resource blocks with
adjacent serial numbers in the same sub-frame are for different antennas.

10. A pilot addition apparatus used in a transmitter for transmitting
data to subscriber of an old system and subscriber of a new system
serving as an updated system of the old system, comprising: a new system
pilot addition judgment unit configured to judge whether or not to insert
a pilot required by the subscriber of the new system into a current
resource block, an insertion position determination unit configured to
determine a sub-carrier symbol block serving as an insertion position of
the pilot required by the subscriber of the new system, from one or more
sub-carrier symbol blocks having a large influence on the statistical
performance for a channel estimation of the subscriber of the old system;
and an insertion unit configured to insert the pilot required by the
subscriber of the new system into the sub-carrier symbol block serving as
the insertion position of the pilot required by the subscriber of the new
system determined by the insertion position determination unit.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of Application PCT/CN2009/074311, filed on
Sep. 29, 2009, now pending, the contents of which are herein wholly
incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a communication system, and
particularly, to a pilot transmission method and apparatus when the
number of the transmitting antennas of a system using the Multiple Input
Multiple Output (MIMO) antenna technique is added.

BACKGROUND OF THE INVENTION

[0003] In the multi-carrier wireless communication based on the Orthogonal
Frequency Division Multiplexing (OFDM) technique, the broadband channel
with a selectively fading frequency is uniformly divided into many
channels with flat fading frequencies, and only a single tap frequency
equalizer is required at the receiving end, which greatly simplifies the
receiver equalization algorithm of the system.

[0004] On the other hand, in order to improve the transmission efficiency
of the wireless system, the MIMO antenna technique has become an
inevitable choice for the current and future wireless communication. In
the MIMO-OFDM system, the usage of multiple transmitting-receiving
antennas greatly increases the number of unknown parameters of the
system, and these unknown parameters shall be estimated using the known
pilot or training signal. In the LTE (LTE Release-8) standard, the
supportable highest configuration of the transmitting-receiving antennas
is 4×4. The precious spectrum resource can be utilized more
effectively under a higher data transmission rate.

[0005] The LTE-A (LTE Release-10) standard requires a configuration of at
most 8×8 transmitting-receiving antennas. In order that the LTE-A
subscriber can accurately estimate the physical channels from 8
transmitting antennas, extra pilots are required, which is a severe
challenge to an efficient and reasonable design of the reference signal.

[0006] The design of the pilot of the 8 transmitting antennas of the LTE-A
system generally requires a forward compatibility. Thus the RS design of
the successive 1 to 4 antennas shall meet the LTE standard. In order that
the LTE-A subscriber estimates the physical channels from 8 transmitting
antennas at the same time of downlink data transmission of the LTE
system, the base station at the transmitting end shall punch some data
sub-carriers of the LTE-A subscriber, and transmit the specific LTE-A
antenna pilot signal on these data sub-carriers.

[0007] During the study of the present invention, the inventor finds that
the current pilot transmission method for the LTE-A still has a large
influence on the LTE system, and this at least because the pilot position
is not properly selected.

[0008] The References for the present invention are listed as follows and
incorporated herein by reference as if they were detailedly described in
this specification.

[0016] The present invention is proposed with respect to the above
conditions of the prior art, so as to reduce the influence of the pilot,
which is inserted into the LTE-A, on the LTE subscriber, and at least
provide a beneficial choice.

[0017] In order to achieve the above object, the following aspects are
proposed according to the embodiments of the present invention:

[0018] Aspect 1: a pilot addition method used in a transmitter for
transmitting data to subscriber of an old system and subscriber of a new
system serving as an updated system of the old system, including:

[0019] judging whether or not to insert a pilot required by the subscriber
of the new system into a current resource block,

[0020] determining a sub-carrier symbol block serving as an insertion
position of the pilot required by the subscriber of the new system, from
one or more sub-carrier symbol blocks having a large influence on the
statistical performance of a channel estimation for the subscriber of the
old system; and

[0021] inserting the pilot required by the subscriber of the new system
into the sub-carrier symbol block serving as the insertion position of
the pilot required by the subscriber of the new system determined by the
determining.

[0022] Aspect 2: the pilot addition method according to aspect 1, wherein
the determining determines the insertion position of the pilot required
by the subscriber of the new system according to a sector.

[0023] Aspect 3: the pilot addition method according to aspect 2, wherein
in case a pilot of an antenna of the new system is located at a
sub-carrier having a serial number k in a certain source block in the
first sector, a sub-carrier for the pilot of the antenna in corresponding
source block in the second sector has a serial number of k+1 modulo k,
and a sub-carrier for the pilot of the antenna in corresponding source
block in the third sector has a serial number of k+2 modulo k, k is a
nonnegative integer.

[0024] Aspect 4: the pilot addition method according to aspect 1, wherein
the old system is an LTE system and the new system is an LTE-A system.

[0025] Aspect 5: the pilot addition method according to aspect 4, wherein
the judging determines inserting the pilot required by the subscriber of
the new system into each of resource blocks in 0th to 3rd
sub-frames, 6th to 9th sub-frames, or 2nd to 9th
sub-frames, or 1st to 4th sub-frames and 6th to 9th
sub-frames of the frame.

[0026] Aspect 6: the pilot addition method according to aspect 5, wherein
the determining determines insertion positions of pilots of two different
antennas in each of the resource blocks;

[0027] Aspect 7: the pilot addition method according to aspect 6, wherein
the determining determines the insertion positions of the pilots of the
two antennas in each of the resource blocks such that pilots added to
resource blocks with the same serial number in adjacent sub-frames are
for different antennas.

[0028] Aspect 8: the pilot addition method according to aspect 6, wherein
the determining determines the insertion positions of the pilots of the
two antennas in each of the resource blocks such that pilots added to
resource blocks with adjacent serial numbers in the same sub-frame are
for different antennas.

[0029] Aspect 9: the pilot addition method according to aspect 4, wherein
the judging determines inserting the pilot required by the subscriber of
the new system into each of resource blocks in a 2nd sub-frame, a
3rd sub-frame, a 7th sub-frame and an 8th sub-frame of the
frame.

[0030] Aspect 10: the pilot addition method according to aspect 9, wherein
the determining determines insertion positions of pilots of four
different antennas in each of the resource blocks;

[0031] Aspect 11: the pilot addition method according to aspect 9, wherein
the determining determines the insertion positions of the pilots of the
four antennas in each of the resource blocks such that pilots added to
resource blocks with the same serial number in adjacent sub-frames are
for different antennas.

[0032] Aspect 12: the pilot addition method according to aspect 9, wherein
the determining determines the insertion positions of the pilots of the
four antennas in each of the resource blocks such that pilots added to
resource blocks with adjacent serial numbers in the same sub-frame are
for different antennas.

[0033] Aspect 13: the pilot addition method according to aspect 4, wherein
the judging determines inserting the pilot required by the subscriber of
the new system into each of resource blocks in any one or two of a
2nd sub-frame, a 3rd sub-frame, a 7th sub-frame and an
8th sub-frame of the frame.

[0034] Aspect 14: the pilot addition method according to aspect 13,
wherein the determining determines insertion positions of pilots of eight
different antennas in each of the resource blocks.

[0035] Aspect 15: the pilot addition method according to aspect 14,
wherein the judging determines inserting the pilot required by the
subscriber of the new system into each of the resource blocks of any two
of the 2nd, 3rd, 7th and 8th sub-frames of the frame,
the pilot is inserted into positions of sub-carrier symbol blocks
determined by symbols with serial numbers 9 and 10 in sub-carriers with
serial numbers 1, 4, 7 and 10 in the resource block.

[0036] Aspect 16: a pilot addition apparatus used in a transmitter for
transmitting data to subscriber of an old system and subscriber of a new
system serving as an updated system of the old system, including:

[0037] a new system pilot addition judgment unit configured to judge
whether or not to insert a pilot required by the subscriber of the new
system into a current resource block;

[0038] an insertion position determination unit configured to determine a
sub-carrier symbol block serving as an insertion position of the pilot
required by the subscriber of the new system, from one or more
sub-carrier symbol blocks having a large influence on the statistical
performance for a channel estimation of the subscriber of the old system;
and

[0039] an insertion unit configured to insert the pilot required by the
subscriber of the new system into the sub-carrier symbol block serving as
the insertion position of the pilot required by the subscriber of the new
system determined by the insertion position determination unit.

[0040] Aspect 17: the pilot addition apparatus according to aspect 16,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system according to sectors.

[0041] Aspect 18: the pilot addition apparatus according to aspect 17,
wherein in case a pilot of an antenna of the new system is located at a
sub-carrier having a serial number k in a certain source block in the
first sector, a sub-carrier for the pilot of the antenna in corresponding
source block in the second sector has a serial number of k+1 modulo k,
and a sub-carrier for the pilot of the antenna in corresponding source
block in the third sector has a serial number of k+2 modulo k, k is a
nonnegative integer.

[0042] Aspect 19: the pilot addition apparatus according to aspect 16,
wherein the old system is an LTE system and the new system is an LTE-A
system.

[0043] Aspect 20: the pilot addition apparatus according to aspect 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in 0th to 3rd sub-frames, 6th to 9th
sub-frames, or 2nd to 9th sub-frames, or 1st to 4th
sub-frames and 6th to 9th sub-frames of the frame.

[0044] Aspect 21: the pilot addition apparatus according to aspect 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in a 2nd sub-frame, a 3rd sub-frame, a 7th
sub-frame and an 8th sub-frame of the frame.

[0045] Aspect 22: the pilot addition apparatus according to aspect 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in any one or two of a 2nd sub-frame, a 3rd
sub-frame, a 7th sub-frame and an 8th sub-frame of the frame.

[0046] Aspect 23: the pilot addition apparatus according to aspect 19,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system in each of the resource blocks such that pilots added to resource
blocks with the same serial number in adjacent sub-frames are for
different antennas.

[0047] Aspect 24: the pilot addition apparatus according to aspect 19,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system in each of the resource blocks such that pilots added to resource
blocks with adjacent serial numbers in the same sub-frames are for
different antennas.

[0049] a first channel model channel estimation error statistical
determination unit configured to determine a statistical distribution of
channel estimation errors of an old system subscriber under a first
channel model;

[0050] a second channel model channel estimation error statistical
determination unit configured to determine a statistical distribution of
channel estimation errors of an old system subscriber under a second
channel model; and

[0051] a new system antenna pilot position determination unit configured
to determine insertion positions of pilots of antennas of a new system in
a sub-frame or RB, according to determination results of the first
channel model channel estimation error statistical determination unit and
the second channel model channel estimation error statistical
determination unit.

[0053] determining a statistical distribution of channel estimation errors
of an old system subscriber under a first channel model;

[0054] determining a statistical distribution of channel estimation errors
of an old system subscriber under a second channel model; and

[0055] determining insertion positions of pilots of antennas of a new
system in a sub-frame or RB, according to determination results of the
above two determining.

[0056] These and further aspects and features of the present invention
will be clearer with reference to the following descriptions and
drawings. In the descriptions and drawings, specific embodiments of the
present invention are disclosed in details to indicate the ways in which
the principle of the present invention may be employed. But it shall be
appreciated that the present invention is not correspondingly limited in
the scope. The present invention includes many changes, modifications and
equivalents within the spirit and clauses of the accompanied claims.

[0057] Features that are described and/or illustrated with respect to one
embodiment may be used in the same or similar way in one or more other
embodiments to be combined with or replace the features of other
embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058]FIG. 1 is a schematic block diagram of a pilot addition apparatus
according to an embodiment of the present invention;

[0059]FIG. 2 is a schematic flowchart of a pilot addition method
according to an embodiment of the present invention;

[0060]FIG. 3 is a schematic diagram of a CRS distribution of an LTE in a
first sector;

[0061] FIG. 4 is a schematic diagram of a CRS distribution of an LTE in a
second sector;

[0062] FIG. 5 is a schematic diagram of a CRS distribution of an LTE in a
third sector;

[0063] FIG. 6 is a statistical distribution diagram of channel estimation
errors under an ITU-PB3 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 3, wherein the gray grids represent
the sub-carrier symbol blocks with poor channel estimation performances;

[0064]FIG. 7 is a statistical distribution diagram of channel estimation
errors under an ITU-VA120 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 3, wherein the gray grids represent
the sub-carrier symbol blocks with poor channel estimation performances;

[0065]FIG. 8 is a schematic diagram of an example of a CSI-RS pattern of
an LTE-A acquired based on FIGS. 6 and 7;

[0066] FIG. 9 is a statistical distribution diagram of channel estimation
errors under an ITU-PB3 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 4, wherein the gray grids represent
the sub-carrier symbol blocks with poor channel estimation performances;

[0067] FIG. 10 is a statistical distribution diagram of channel estimation
errors under an ITU-VA120 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 4, wherein the gray grids represent
the sub-carrier symbol blocks with poor channel estimation performances;

[0068] FIG. 11 is a schematic diagram of an example of a CSI-RS pattern of
an LTE-A acquired based on FIGS. 9 and 10;

[0069] FIG. 12 is a distribution diagram of channel estimation errors
under an ITU-PA3 km/h channel based on an RS as illustrated in FIG. 5,
wherein the gray grids represent the sub-carrier symbol blocks with poor
channel estimation performances;

[0070] FIG. 13 is a distribution diagram of channel estimation errors
under an ITU-VA 120 km/h channel based on an RS as illustrated in FIG. 5,
wherein the gray grids represent the sub-carrier symbol blocks with poor
channel estimation performances;

[0071] FIG. 14 is a schematic diagram of an example of a CSI-RS pattern of
an LTE-A based on FIGS. 12 and 13;

[0072]FIG. 15 is a schematic diagram of another example of a CSI-RS
pattern of an LTE-A based on the second sector;

[0073] FIG. 16 illustrates an example of RS placement according to a first
embodiment of the present invention;

[0074] FIG. 17 illustrates an example of RS placement according to a
second embodiment of the present invention;

[0075] FIG. 18 illustrates an example of RS placement according to a third
embodiment of the present invention;

[0076]FIG. 19 illustrates an example of RS resource block into which
LTE-A is inserted, in the RS placement according to a fourth embodiment
of the present invention;

[0077] FIGS. 20-21 illustrate, respectively, schematic structure diagrams
of a transmitter and a receiver of an LTE-A according to an embodiment of
the present invention which are backward compatible with an LTE;

[0078]FIG. 22 illustrates a functional block diagram of a pilot insertion
position determination apparatus according to an embodiment of the
present invention;

[0079]FIG. 23 illustrates a flowchart of a pilot insertion position
determination method according to an embodiment of the present invention;

[0080]FIG. 24 illustrates a block diagram of a computer capable of
implementing the method and apparatus according to the embodiments of the
present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0081] The embodiments of the present invention are detailedly described
as follows with reference to the drawings. In order to be clear and
concise, not all the features of the embodiments are described in the
specification. However, it shall be appreciated that during the process
of developing any of these embodiments, many specific decisions of the
embodiment must be made to realize the developer's object. For example,
the constraint conditions relevant to the system and service are
satisfied, and these constraint conditions may vary with the embodiments.
In addition, it shall be noted that although the development may be very
complex and time consuming, the development is just a routine task for a
person skilled in the art who benefits from the disclosure.

[0082] To be noted, in order to avoid the present invention from being
vague due to unnecessary details, the drawings only illustrate device
structures and/or processing steps closely related to the solution
according to the present invention, while omitting other details not so
closely related.

[0083] Before detailedly describing the embodiments of the present
invention, some concepts of the prior art relevant to the present
invention are introduced as follows.

[0084] In order to allocate the physical resources in a high efficiency, a
physical frame is usually divided into many Transmitting Time Intervals
(TTIs) in the time domain, and divided into many basic allocation units
in the frequency domain. For example, in the latest LTE standard, one
frame includes 10 TTIs each having 14 OFDM symbols; each TTI is divided
into sub-blocks in a unit of 12 sub-carriers in the frequency domain; and
a time-frequency resource block (hereinafter referred to as Resource
Block (RB)) of 12 sub-carriers and 14 OFDM symbols constitute a basic
physical resource unit. That is, one TTI includes a number of (e.g., 50)
RBs continuous in the frequency domain. In the embodiments of the present
invention, the TTI is also referred to as a sub-frame. In addition, 10
sub-frames in one frame are numbered as the 0th to 9th
sub-frames, 14 symbols in one sub-frame are numbered as the 0th to
13th symbols, and 12 sub-carriers in one RB are numbered as the
0th to 11th sub-carriers.

[0085] Further, the reference signal design scheme for the multi-output
antenna system is mainly based on the orthogonal Reference Signal (RS)
design criterion, i.e., the resource elements occupied by the RSs of
respective transmitting antennas are orthogonal to each other, thereby
avoiding the mutual interference at the receiving end. The embodiments of
the present invention are also described under the condition that the
orthogonal RS design criterion is adopted. But the embodiments of the
present invention are not limited to such condition, and other design
criterions may also be used.

[0086] In the time-frequency 2D physical resource, when the Common
Reference Signal (CRS) and data of the LTE and the CRS of the LTE-A are
both existed, the CRS of the LTE-A cannot be overlapped with that of the
LTE, and can only be placed on the data sub-carrier of the LTE by means
of punching.

[0087] The inventor of the present invention studies the issue of
transmitting pilots with the 8 transmitting antennas of the LTE-A system,
and makes the following conclusion: the subscriber of the LTE shall carry
out a channel estimation of all data sub-carriers of a received sub-frame
before demodulating and decoding the received sub-frame, while the
sub-carriers with poor channel estimation performance (i.e., certain
specific sub-carriers, such as those far away from the pilot, whose
channel estimation has a large relative error) has an obvious influence
on the demodulating and decoding performance, thus the influence on the
LTE frame decoding will be reduced by punching those sub-carriers.

[0088] In the embodiments of the present invention, the antennas used by
the LTE system are called as LTE antennas (e.g., antennas 0-3), while the
antennas used by the LTE-A system are called as LTE-A antennas (e.g.,
antennas 0-7). The pilots transmitted by the LTE antennas are called as
LTE pilots, while the pilots transmitted by the LTE-A antennas are called
as LTE-A pilots.

[0089] A pilot addition apparatus according to an embodiment of the
present invention will be described as follows. FIG. 1 schematically
illustrates a block diagram of a pilot addition apparatus according to an
embodiment of the present invention. As illustrated in FIG. 1, a pilot
addition unit 100 according to an embodiment of the present invention
includes:

[0090] an LTE-A pilot addition judgment unit 110 configured to judge
whether or not to insert an LTE-A pilot into current sub-frame, and if
yes, further judge for each RB of the sub-frame whether or not to insert
the LTE-A pilot;

[0091] an insertion position determination unit 120 configured to
determine an insertion position of the LTE-A pilot, wherein the insertion
position is located on a sub-carrier symbol block having a large
influence on the statistical performance for a channel estimation of an
LTE subscriber; and

[0092] an insertion unit 130 configured to insert the LTE-A pilot into the
insertion position of the LTE-A pilot determined by the insertion
position determination unit 120.

[0093]FIG. 2 schematically illustrates a flowchart of a pilot addition
method according to an embodiment of the present invention. As
illustrated in FIG. 2, a pilot addition method according to an embodiment
of the present invention includes:

[0094] S210: judging whether or not to insert an LTE-A pilot into current
sub-frame, and if yes, further judging for each RB of the sub-frame
whether or not to insert the LTE-A pilot;

[0095] S220: determining an insertion position of the LTE-A pilot, wherein
the insertion position is located on a sub-carrier symbol block having a
large influence on the statistical performance for a channel estimation
of an LTE subscriber; and

[0096] S230: inserting the LTE-A pilot into the insertion position of the
LTE-A pilot determined by the insertion position determination unit 120.

[0097] Next, the operation of the insertion position determination unit
120 and step S220 will be described in details.

[0098] Firstly, it will be described how to determine the sub-carrier
symbol block having a large influence on the statistical performance for
the channel estimation of the LTE subscriber.

[0099] FIGS. 3-5 illustrate the CRS positions (also referred to as pilot
patterns) in the RB with respect to first to third sectors of an LTE,
respectively (herein the first to third sectors belong to the same cell
and are separated from each other by different orientations in the space;
the spatial angle ranges covered by the three sectors are 10-120°,
121°-240° and 241°-360°, respectively). In
the drawings, the horizontal axis represents different OFDM symbols and
the longitudinal axis represents different sub-carriers.

[0100] Since the channel estimation algorithm is based on one or more RBs,
the LTE data sub-carrier with poor channel estimation statistical
performance may be determined according to the number and positions of
the RSs in a specific region or through a simulation test.

[0101] FIG. 6 is a statistical distribution diagram of LTE subscriber
channel estimation errors under an ITU-PB3 km/h channel model with
respect to the CRS distribution as illustrated in FIG. 3, and FIG. 7 is a
statistical distribution diagram of LTE subscriber channel estimation
errors under an ITU-VA120 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 3. In the drawings, the horizontal
axis represents different OFDM symbols and the longitudinal axis
represents different sub-carriers.

[0102] FIGS. 6 and 7 each has four sub-diagrams corresponding to the four
transmitting antennas of the LTE system, respectively.

[0103] The channel estimation algorithm for example may adopt the
2-dimension minimum means square error (2D MMSE) criterion based on one
RB. With which, the channel estimation value on any grid (on the
sub-carrier symbol block) in the one RB is:

hi,j={tilde over (w)}i,j{tilde over (h)}p (1)

[0104] Herein hi,j is an estimation value of a channel response on
the jth OFDM symbol of the ith sub-carrier of a certain RB,
{tilde over (h)}p is a column vector consisting of channel responses
of all pilot points in the RB, and {tilde over (w)}i,j is an
interpolation vector using the 2D MMSE criterion. The above channel
estimation algorithm is not limited to the 2D MMSE criterion, and other
linear interpolation method may also be used, wherein the form of channel
estimation is completely the same as Equation (1), and only the element
value of {tilde over (w)}i,j is different. The statistical value of
the channel estimation error on each sub-carrier of one RB is

Ei,j=E[|hi,j-hi,j|2] (2)

[0105] Herein E[.] is an operation for mathematical expectation.

[0106] As can be seen from FIGS. 6-7, the statistical error of the channel
estimation on the shadowed sub-carrier symbol block is large, which is
caused by the CRS distribution on the RB. On this basis, in order to
punch the sub-carrier at an appropriate position to place the LTE-A CRS
while reducing the influence on the LTE data demodulating and decoding
performance, the LTE data sub-carrier with a large channel estimation
error is punched. Since different statistical error distributions of
channel estimations may be obtained under different channel model
conditions, the embodiments of the present invention consider the channel
estimation error performances under different channel models, so as to
improve the applicability of the LTE-A RS design obtained based on the
method according to the embodiment of the invention. ITU-PB 3 km/h and
ITU-VA 120 km/h are two typical channel models, thus they are taken as
examples and described in the embodiments of the present invention. It
shall be appreciated that other channel model(s) shall be used to replace
one or both of these channel models, or combine with the two channel
models to determine the LTE data sub-carrier with a large channel
estimation error. Herein the two channel models are just exemplary, and
the actual design may be based on other channel models recommended by the
International Telecommunication Union (ITU), e.g., the PB or VA channel
corrected under different moving speeds.

[0107] As can be seen from FIG. 6, the statistical errors of the channel
estimations on the following sub-carrier symbol blocks are larger for LTE
antennas 0-3 under the ITU-PB 3 km/h channel model:

[0115] Thus appropriate positions can be selected according to the above
order and in combination with other constraint conditions (e.g., the
LTE-A CRS cannot be overlapped with the LTE CRS, some positions are
occupied by other dedicated data, etc.).

[0116] For example on the basis of FIGS. 6-7, when the LTE-A RS needs to
be placed in a certain RB, it may be placed in any of the three grids at
the upper right corner of the RB. In addition, it shall be noted that for
the convenience of description, the statistical errors of the channel
estimations on the sub-carrier grids are simply classified into large and
small errors. But in fact, the error may be determined according to the
concrete value, so as to judge the sub-carrier to which the LTE-A RS
shall be placed.

[0117] In consideration of other constraint conditions and by means of the
simulation, the inventor finds that the LTE-A RS pattern as illustrated
in FIG. 8 can be adopted.

[0118] In FIG. 8, the grid marked as antennas 0-7 represents the position
where the pilot of corresponding LTE-A transmitting antenna may be
placed.

[0119] To be noted, the LTE-A RS pattern as illustrated in FIG. 8 is just
an exemplary distribution in case the pilots of two antennas are to be
inserted into the RB and some positions (e.g., the two grids
corresponding to the 11th sub-carrier and the two grids
corresponding to the 10th grid at the upper right corner) has been
occupied, rather than a limitation to the present invention. A person
skilled in the art shall appreciate that other positions can be selected
upon the actual conditions to be used together with or replace the two
positions.

[0120] As can be seen from FIGS. 6-7, the RS pattern as illustrated in
FIG. 8 has a small influence on the data demodulating and decoding
performance of the LTE system. Thus the pattern as illustrated in FIG. 8
may be used for the LTE-A CSI-RS of the first sector, and it has a small
influence on the LTE system.

[0121] FIG. 9 is a statistical distribution diagram of LTE subscriber
channel estimation errors under an ITU-PB 3 km/h channel model with
respect to the CRS distribution as illustrated in FIG. 4, FIG. 10 is a
statistical distribution diagram of LTE subscriber channel estimation
errors under an ITU-VA120 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 4, and FIG. 11 illustrates an example
of an LTE-A CSI-RS pattern acquired based on FIGS. 9 and 10 and in
consideration of other constraint conditions. As illustrated in FIG. 11,
in the second sector, the LTE-A RS may be placed in two grids with the
coordinates of (12, 7) and (13, 7).

[0122] Similarly, the LTE-A RS pattern as illustrated in FIG. 11 is just
an exemplary distribution in case the pilots of two antennas are to be
inserted into the RB and some positions has been occupied, rather than a
limitation to the present invention. A person skilled in the art shall
appreciate that other positions can be selected upon the actual
conditions to be used together with or replace the two positions.

[0123] FIG. 12 is a statistical distribution diagram of LTE subscriber
channel estimation errors under an ITU-PB3 km/h channel model with
respect to the CRS distribution as illustrated in FIG. 5, FIG. 13 is a
statistical distribution diagram of LTE subscriber channel estimation
errors under an ITU-VA120 km/h channel model with respect to the CRS
distribution as illustrated in FIG. 5, and FIG. 14 illustrates an LTE-A
CSI-RS pattern acquired based on FIGS. 12 and 13 and in consideration of
other constraint conditions. As illustrated in FIG. 14, in the third
sector, the LTE-A RS may be placed in two grids with the coordinates of
(12, 2) and (13, 2).

[0124] Similarly, the LTE-A RS pattern as illustrated in FIG. 14 is just
an exemplary distribution in case the pilots of two antennas are to be
inserted into the RB and some positions are occupied, rather than a
limitation to the present invention. A person skilled in the art shall
appreciate that other positions can be selected upon the actual
conditions to be used together with or replace the two positions

[0125] The above positions for placing the LTE-A CRS in the RB as
illustrated in FIGS. 8, 11 and 14 are just exemplary, for example in case
the pilots of 4 LTE-A antennas are placed in the second sector, the LTE-A
CRS may also be placed as illustrated in FIG. 15. FIG. 15 illustrates
another example of a distribution diagram of RBs wherein the LTE-A CRSs
are placed in the second sector.

[0126] To be noted, the above descriptions only concern the channel
estimation of a single RB. But in the actual implementation of the
channel estimation, a combined channel estimation may be required for
continuous RBs, and the acquired channel estimation error may be
different from the statistical error distributions in the above drawings.
For example, a combined channel estimation may be carried out using 4 or
8 continuous RBs in the frequency domain. Thus the error distributions in
FIGS. 6, 7, 9, 10, 12 and 13 may be changed above each RB, and
corresponding error distribution rules shall be re-inspected to obtain
corresponding LTE-A RS patterns.

[0127] In addition, the above descriptions only concern the CRS positions
in the RB when the LTE-A CRSs shall be placed in the RB. But the number
of the LTE-A CRSs is small, e.g., currently the CRS has a cycle of 5 ms
or 10 ms in the time axis and a cycle of 6 or 12 sub-carriers in the
frequency axis. Thus the positions of the RBs for placing the RSs shall
be determined, e.g., determining the positions of the RBs for placing the
RSs among totally 500 RBs in 10 ms. The criterion for determining the
positions for example may be a criterion of minimizing the CSI estimation
error, i.e., selecting specific RBs to place the CRSs so that the CSI
estimation is the most accurate. Other criterions may also be adopted to
determine the positions of the RBs for placing the RSs.

[0128] Next, the implementations of placing the RSs according to the
embodiments of the present invention will be described, which are just
exemplary rather than limitations to the present invention.

[0129] RS Placement According to the First Embodiment

[0130] According to the embodiment of the present invention, Rss for the
LTE-A subscriber (LTE-A RSs) are transmitted on 8 specific sub-frames in
each frame, and other sub-frames are only used to transmit RSs for the
LTE subscriber (LTE RSs). For example, the LTE-A RSs may be inserted into
the 0th to 3rd and the 6th to 9th sub-frames, the
2nd to 9th sub-frames or the 1st to 4th and the
6th to 9th sub-frames in each frame.

[0131] FIG. 16 illustrates an example of RS placement according to a first
embodiment of the present invention. As illustrated in FIG. 16, the
pilots of 8 antennas of the LTE-A subscriber are placed in the 2nd
to 9th sub-frames. In FIG. 16, the digits 0-9 in the top row
represent the serial numbers of the sub-frames in the current frame, and
the digits (12 in FIG. 16) with smaller sizes near the digits 0-9 in the
top row represent the symbols arranged with the pilots of the LTE-A
subscriber in the sub-frame. The digit in each large grid (0-7 in FIG.
16) represents the RB serial number in the current frame. In the 2nd
to 9th sub-frames, in the small grid indicates that the CSI-RS of a
kth transmitting antenna is placed at the position, wherein k=0, 1,
2, 3, 4, 5, 6 or 7. The digit in front of represents the serial number
of the sub-carrier in one RB.

[0132] In the embodiment as illustrated in FIG. 16, the RSs of two
different antennas are placed in each RB of each of the 2nd to
9th sub-frames, and the RSs placed in the RBs adjacent to each other
of each sub-frame are for different antennas. For example as illustrated
in FIG. 16, in the 2nd sub-frame, the RSs of the 0th and
4th antennas are placed in the 2nd and 8th sub-carriers in
the 0th RB, the RSs of the 1st and 5th antennas are placed
in the 2nd and 8th sub-carriers in the 1st RB, the RSs of
the 2nd and 6th antennas are placed in the 2nd and
8th sub-carriers in the 2nd RB, and the RSs of the 3rd and
7th antennas are placed in the 2nd and 8th sub-carriers in
the 3rd RB.

[0133] Further, the RSs placed in the RBs with the same serial number in
adjacent sub-frames are also for different antennas. As illustrated in
FIG. 16, the RSs of the 0th and 4th antennas are placed in the
2nd and 8th sub-carriers in the 0th RB in the 2nd
sub-frame, and the RSs of the 2nd and 6th antennas are placed
in the 2nd and 8th sub-carriers in the 0th RB in the
3rd sub-frame. The RSs of the 1st and 5th antennas are
placed in the 2nd and 8th sub-carriers in the 1st RB in
the 2nd sub-frame, and the RSs of the 3rd and 7th antennas
are placed in the 2nd and 8th sub-carriers in the 1st RB
in the 3rd sub-frame. The RSs of the 2nd and 6th antennas
are placed in the 2nd and 8th sub-carriers in the 2nd RB
in the 2nd sub-frame, and the RSs of the 0th and 4th
antennas are placed in the 2nd and 8th sub-carriers in the
2nd RB in the 3rd sub-frame, and so on.

[0134] To be noted, in the embodiment as illustrated in FIG. 16, in each
RB the RSs for various antennas are placed at the 12th symbol of the
2nd sub-carrier and the 12th symbol of the 8th
sub-carrier, respectively, which is just exemplary rather than
limitations to the present invention. Corresponding positions (i.e.,
positions of sub-carriers and symbols having the largest influence on the
statistical error of LTE subscriber channel estimation) may be selected
according to the above method for selecting sub-carriers for each or
multiple RBs.

[0135] RS Placement According to the Second Embodiment

[0136] According to this embodiment, LTE-A RSs are transmitted on 4
specific sub-frames in a frame, and other sub-frames are only used to
transmit LTE RSs. For example, the LTE-A RSs may be inserted into the
2nd, 3rd, 7th and 8th sub-frames in each frame.

[0137] FIG. 17 illustrates an example of RS placement according to a
second embodiment of the present invention. As illustrated in FIG. 17,
the pilots of 8 antennas of the LTE-A subscriber are placed in the
2nd, 3rd, 7th and 8th sub-frames. The symbol meanings
in FIG. 17 are the same as those in FIG. 16.

[0138] In the embodiment as illustrated in FIG. 17, the RSs of four
different antennas are placed in each RB of each of the 2nd,
3rd, 7th and 8th sub-frames, and the RSs placed in the
adjacent RBs of each sub-frame are for different antennas. For example as
illustrated in FIG. 17, in the 2nd sub-frame, the RSs of the
0th, 2nd, 4th and 6th antennas are placed in the
1st, 4th, 7th and 10th sub-carriers in the 0th
RB, the RSs of the 1st, 3rd, 5th and 7th antennas are
placed in the 1st, 4th, 7th and 10th sub-carriers in
the 1st RB, and so on.

[0139] Further, the RSs placed in the RBs with the same serial number in
adjacent sub-frames are also for different antennas. As illustrated in
FIG. 17, the RSs of the 0th, 2nd, 4th and 6th
antennas are placed in the 1st, 4th, 7th and 10th
sub-carriers in the 0th RB in the 2nd sub-frame, and the RSs of
the 7th, 5th, 3rd and 1st antennas are placed in the
1st, 4th, 7th and 10th sub-carriers in the 0th
RB in the 3rd sub-frame. The RSs of the 1st, 3rd, 5th
and 7th antennas are placed in the 1st, 4th, 7th and
10th sub-carriers in the 1st RB in the 2nd sub-frame, and
the RSs of the 6th, 4th, 2nd and 0th antennas are
placed in the 1st, 4th, 7th and 10th sub-carriers in
the 1st RB in the 3rd sub-frame, and so on.

[0140] To be noted, in the embodiment as illustrated in FIG. 17, in each
RB the RSs for various antennas are placed at the 10th symbols of
the 1st, 4th, 7th and 10th sub-carriers,
respectively, which is just exemplary rather than limitations to the
present invention. Corresponding positions (i.e., positions of 4
sub-carriers and symbols having the largest influence on the statistical
error of LTE subscriber channel estimation) may be selected according to
the above method for selecting sub-carriers for each or multiple RBs.

[0141] RS Placement According to the Third Embodiment

[0142] According to this embodiment, LTE-A RSs are transmitted on 2
specific sub-frames in each frame, and other sub-frames are only used to
transmit LTE RSs. For example, the LTE-A RSs may be inserted into the
2nd and 7th, 3rd and 8th, 2nd and 8th and
3rd and 7th sub-frames in each frame.

[0143] FIG. 18 illustrates an example of RS placement according to a third
embodiment of the present invention. As illustrated in FIG. 18, the
pilots of 8 antennas of the LTE-A subscriber are placed in each RB of the
2nd and 8th sub-frames. The symbol meanings in FIG. 18 are the
same as those in FIG. 16.

[0144] To be noted, in the embodiment as illustrated in FIG. 18, in each
RB the RSs for various antennas are placed at the 9th and 10th
symbols of the 1st, 4th, 7th and 10th sub-carriers,
respectively, which is just exemplary rather than limitations to the
present invention. Corresponding positions (i.e., positions of 8
sub-carriers and symbols having the largest influence on the statistical
error of LTE subscriber channel estimation) may be selected according to
the method for selecting sub-carriers for each or multiple RBs.

[0145] RS Placement According to the Fourth Embodiment

[0146] According to this embodiment, LTE-A RSs are transmitted in all RBs
on one specific sub-frame in each frame, and other sub-frames are only
used to transmit LTE RSs. For example, the LTE-A RSs may be inserted into
any of the 2nd, 3rd, 7th and 8th sub-frames in each
frame.

[0147]FIG. 19 illustrates, in RS placement according to a fourth
embodiment of the present invention, an example of RB into which LTE-A RS
is inserted. As illustrated in FIG. 19, among the RBs for being inserted
with the LTE-A RSs, the 9th and 10th symbols and the 0th
to 3rd and the 8th to 11th sub-carriers are inserted with
the RSs for respective antennas.

[0148] In addition, for the same symbol position, the RSs for different
antennas are inserted into adjacent sub-carriers. For example, for the
position of the 9th symbol, the RS for antenna 6 is inserted into
the 8th sub-carrier, while the RS for antenna 4 is inserted into the
9th sub-carrier.

[0149] In addition, for the same sub-carrier position, the RSs for
different antennas are inserted into adjacent symbols. For example, for
the position of the 8th sub-carrier, the RS for antenna 6 is
inserted into the 9th symbol, while the RS for antenna 7 is inserted
into the 10th symbol.

[0150] Similarly, the embodiment illustrated in FIG. 19 is just exemplary,
and corresponding positions (i.e., positions of 8 sub-carriers and
symbols having the largest influence on the statistical error of LTE
subscriber channel estimation) may be selected according to the above
method for selecting sub-carriers for each or multiple RBs.

[0151] In addition, although in the above embodiment the LTE-A pilots are
inserted into each RB in the selected sub-frame, it shall be noted other
embodiment is also practical, e.g., the pilots may be inserted into a
certain number of RBs in the selected sub-frame.

[0152] Further, in consideration of the sector, the position of each RS in
the sub-carrier is cyclically shifted according to different sectors,
i.e., when a CSI-RS is in a sub-carrier with a serial number k in a
certain RB in the 0th sector, it is in sub-carriers with serial
numbers k+1 modulo k and k+2 modulo k, or k-1 modulo k and k-2 modulo k
in corresponding RBs in the 1st and 2nd sectors, respectively,
herein k for example is 3 or 12. The value of x modulo y is a remainder
obtained by dividing x with y. The criterion of the cyclic shift is to
avoid mutual interference between LTE-A CSI-RSs of different sectors.

[0153] To be noted, it is unnecessary for the insertion position
determination unit 120 and step S220 to determine which positions are
preferable for insertion, and the insertion positions may be directly
determined according to the various positions predetermined by the above
methods, the pre-negotiated between the transmitter and the receiver, the
sub-frame positions in the frame, the RB positions in the sub-frame, and
the serial numbers of the sub-carriers or symbols.

[0154] In step S210, the LTE-A pilot addition judgment unit 110 may
determine whether or not to insert the LTE-A pilot into the sub-frame by
determining whether the data is transmitted to the LTE subscriber or the
LTE-A subscriber. In another embodiment, the LTE-A pilot addition
judgment unit 110 determines whether or not to insert the LTE-A pilot
into the sub-frame according to the system configuration or whether or
not the service request of the LTE-A subscriber is existed.

[0155] In step S230, any method well known or to be conceived by a person
skilled in the art may be adopted by the insertion unit 130 to punch the
data sub-carrier and insert the LTE-A pilot, and herein is not described
in details.

[0156] FIGS. 20-21 respectively show structure diagrams of transmitter and
receiver of an LTE-A backward compatible with an LTE and using an LTE-A
pilot transmitting apparatus or method according to an embodiment of the
present invention. As illustrated in FIG. 20, the original information
bit is firstly coded by a coder, then a symbol modulator maps the coded
bit information into a symbol constellation diagram such as QPSK, 16QAM
or 64QAM, and a space-time coder maps the single channel signal into the
multi-channel signal to be transmitted. In that case, it is determined
whether or not to insert the LTE-A CSI-RS using the pilot addition method
or apparatus according to the embodiment of the present invention as
described above, for example according to the system configuration or the
existence of the service request of the LTE-A subscriber. If yes, the
insertion positions are determined according to the predetermined LTE-A
CSI-RS pattern, and the LTE-A CSI-RSs are inserted by punching the LTE
data sub-carriers. Next, operations such as serial-to-parallel
conversion, inverse FFT, CP addition, etc. on each channel of signals
added with the pilots are carried out, respectively. And finally, the
signals are transmitted to the wireless physical channel through a
plurality of transmitting antennas. As illustrated in FIG. 21,
corresponding inverse operation is made at the receiving end of the LTE
subscriber: after the receiving antenna receives a signal from the
transmitter, removing the CP at first, then performing an FFT and a
parallel-to-serial conversion, and extracting an RS according to the LTE
RS pattern; performing a channel estimation, a space-time decoding or a
space-time equalization based on the RS, and finally restoring the
transmitted original information bit through a channel decoding. At the
receiving end of the LTE-A subscriber, extracting a CSI-RS according to
the LTE-A CSI-RS pattern, and based on the CSI-RS, performing operations
such as channel estimation, Channel Quality Indication (CQI) calculation,
and Precoding Matrix Index (PMI) calculation.

[0157] According to the present invention, the overhead of the CSI-RSs for
estimating the LTE-A channel state information is small, that is, the
amount of the CSI-RSs for estimating the channel state information of 8
transmitting antennas is only 0.96%. In addition, the positions of these
CSI-RSs are selected to be on the data sub-carriers of the LTE subscriber
with poor channel estimation performances. Finally, since the design of
the LTE-A CSI-RS considers the backward compatibility, the insertion and
usage of the CSI-RS are easily to be realized.

[0158] To be noted, although the LTE system (old system) and the LTE-A
system (new system) serving as the updated system are taken as examples
in the above descriptions of the embodiments of the present invention, it
shall be appreciated that the descriptions are just exemplary, and the
embodiments of the present invention are applicable to any condition
where antennas of the transmitter of the multi-antenna system are
increased. When a multi-antenna system (e.g., an LTE-A system having at
most 8 transmitting antennas) is updated to a system having more
transmitting antennas (e.g., a system having 10 or more antennas), pilots
of the added transmitting antennas may be inserted into appropriate
sub-carrier symbol blocks according to the influence on the subscriber
channel estimation of the original system by each sub-carrier symbol
block.

[0159]FIG. 22 illustrates a functional block diagram of a pilot insertion
position determination apparatus according to an embodiment of the
present invention.

[0160] As illustrated in FIG. 22, a pilot insertion position determination
apparatus 300 according to the embodiment of the present invention
includes a first channel model channel estimation error statistical
determination unit 310, a second channel model channel estimation error
statistical determination unit 320, and a new system antenna pilot
position determination unit 330.

[0161] The first channel model channel estimation error statistical
determination unit 310 is configured to determine a statistical
distribution of channel estimation errors of an old system (e.g., LTE
system) subscriber under a first channel model. The first channel model
for example is an ITU-PB3 km/h channel model. The channel estimation for
example is based on one or more sub-carriers in the RB.

[0162] The second channel model channel estimation error statistical
determination unit 320 is configured to determine a statistical
distribution of channel estimation errors of an old system (e.g., LTE
system) subscriber under a second channel model. The second channel model
for example is an ITU-VA120 km/h channel model. The channel estimation
for example is based on one or more sub-carriers in the RB. To be noted,
the number of sub-carriers based on which the channel estimation by the
second channel model channel estimation error statistical determination
unit 320 is performed shall be identical to that of sub-carriers based on
which the channel estimation by the first channel model channel
estimation error statistical determination unit 310 is performed.

[0163] The new system antenna pilot position determination unit 330 is
configured to determine insertion positions of pilots of antennas of the
new system in a sub-frame or RB, according to determination results of
the first channel model channel estimation error statistical
determination unit 310 and the second channel model channel estimation
error statistical determination unit 320. The insertion positions of the
pilots of the antennas of the new system in the sub-frame or RB may be
determined according to the influence on the channel estimation of the
old system subscriber by each sub-carrier symbol block and some
constraint conditions (e.g., whether the sub-carrier symbol block has
been occupied).

[0164]FIG. 23 illustrates a flowchart of a pilot insertion position
determination method according to an embodiment of the present invention.

[0165] As illustrated in FIG. 23, the pilot insertion position
determination method according to the embodiment of the present invention
includes:

[0166] Step S410: a first channel model channel estimation error
statistical determination unit 310 determines a statistical distribution
of channel estimation errors of an old system (e.g., LTE system)
subscriber under a first channel model. The first channel model for
example is an ITU-PB3 km/h channel model. The channel estimation for
example is based on one or more sub-carriers in the RB.

[0167] Step S420: a second channel model channel estimation error
statistical determination unit 320 determines a statistical distribution
of channel estimation errors of an old system (e.g., LTE system)
subscriber under a second channel model. The second channel model for
example is an ITU-VA120 km/h channel model. The channel estimation for
example is based on one or more sub-carriers in the RB. To be noted, the
number of sub-carriers based on which the channel estimation by the
second channel model channel estimation error statistical determination
unit 320 is performed shall be identical to that of sub-carriers based on
which the channel estimation by the first channel model channel
estimation error statistical determination unit 310 is performed.

[0168] Step S430: a new system antenna pilot position determination unit
330 determines insertion positions of pilots of antennas of the new
system in a sub-frame or RB, according to determination results of the
first channel model channel estimation error statistical determination
unit 310 and the second channel model channel estimation error
statistical determination unit 320. The insertion positions of the pilots
of the antennas of the new system in the sub-frame or RB may be
determined according to the influence on the channel estimation of the
old system subscriber by each sub-carrier symbol block and some
constraint conditions (e.g., whether the sub-carrier symbol block has
been occupied).

[0169] Various constituent modules, units and subunits in the above
apparatus as well as various steps in the above method may be configured
through software, firmware, hardware or combinations thereof. The
configuring means or manners are well known by a person skilled in the
art, and herein are not repeated. In case of the implementation through
software or firmware, programs constructing the software shall be
installed from a storage medium or network to a computer with dedicated
hardware structure (e.g., a general computer as illustrated in FIG. 24)
or a computer combined in a system or apparatus (e.g., a transmitter),
and the computer can perform various functions when being installed with
various programs.

[0170]FIG. 24 illustrates a block diagram of a computer capable of
implementing the method and apparatus according to the embodiments of the
present invention.

[0171] In FIG. 24, a Central Processing Unit (CPU) 2401 performs various
processing according to programs stored in a Read Only Memory (ROM) 2402
or programs loaded from a storage section 2408 to a Random Access Memory
(RAM) 2403. Data required by the CPU 2401 to perform various processing
shall be stored in the RAM 2403 as necessary. The CPU 2401, the ROM 2402
and the RAM 2403 are connected to each other via a bus 2404. An
Input/Output (I/O) interface 2405 may also be connected to the bus 2404
upon request.

[0172] Upon request the following components may be connected to the I/O
interface 2405: an input section 2406 (including keypad, mouse, etc.), an
output section 2407 (including display such as Cathode-Ray Tube (CRT) and
Liquid Crystal Display (LCD), and loudspeaker, etc.), a storage section
2408 (including hard disk, etc.) and a communication section 2409
(including network interface card such as LAN card, modem, etc.). The
communication section 2409 for example performs a communication
processing through a network such as Internet. A driver 2410 may also be
connected to the I/O interface 2405 as necessary. A detachable medium
2411 such as magnetic disk, optical disk, magnetic optical disk,
semiconductor memory, etc. may be mounted on the driver 2410 as
necessary, so that the computer program read therefrom will be installed
into the storage section 2408 upon request.

[0173] In case the above series of processing is implemented through
software, programs constructing the software shall be installed from a
network such as the Internet or a storage medium such as the detachable
medium 2411.

[0174] A person skilled in the art shall appreciate that the storage
medium is not limited to the detachable medium 2411 as illustrated in
FIG. 24 which stores programs and was distributed independently from the
device to provide the programs to the subscriber. The detachable medium
2411 for example includes magnetic disk (including floppy disk
(registered trademark)), compact disk (including Compact Disk Read Only
Memory (CD-ROM) and Digital Versatile Disk (DVD)), magnetic optical disk
(including Mini Disk (MD) (registered trademark)) and semiconductor
memory. Or the storage medium may be the ROM 2402, the hard disk in the
storage section 2408, etc. in which programs are stored and distributed
to the subscriber together with the device containing them.

[0175] The present invention further provides a program product that
stores machine readable instruction codes capable of executing the above
method according to the embodiment of the present invention when being
read and executed by a machine.

[0176] Accordingly, a storage medium for loading the program product that
stores the machine readable instruction codes is also included in the
disclosure of the present invention. The storage medium includes, but not
limited to, floppy disk, optical disk, magnetic optical disk, memory
card, memory stick, etc.

[0177] Excursus 1: a pilot addition method used in a transmitter for
transmitting data to subscriber of an old system and subscriber of a new
system serving as an updated system of the old system, including:

[0178] judging whether or not to insert a pilot required by the subscriber
of the new system into a current resource block,

[0179] determining a sub-carrier symbol block serving as an insertion
position of the pilot required by the subscriber of the new system, from
one or more sub-carrier symbol blocks having a large influence on the
statistical performance of a channel estimation for the subscriber of the
old system; and

[0180] inserting the pilot required by the subscriber of the new system
into the sub-carrier symbol block serving as the insertion position of
the pilot required by the subscriber of the new system determined by the
determining.

[0181] Excursus 2: the pilot addition method according to excursus 1,
wherein the determining determines the insertion position of the pilot
required by the subscriber of the new system according to a sector.

[0182] Excursus 3: the pilot addition method according to excursus 2,
wherein in case a pilot of an antenna of the new system is located at a
sub-carrier having a serial number k in a certain source block in the
first sector, a sub-carrier for the pilot of the antenna in corresponding
source block in the second sector has a serial number of k+1 modulo k,
and a sub-carrier for the pilot of the antenna in corresponding source
block in the third sector has a serial number of k+2 modulo k, k is a
nonnegative integer.

[0183] Excursus 4: the pilot addition method according to excursus 1,
wherein the old system is an LTE system and the new system is an LTE-A
system.

[0184] Excursus 5: the pilot addition method according to excursus 4,
wherein the judging determines inserting the pilot required by the
subscriber of the new system into each of resource blocks in 0th to
3rd sub-frames, 6th to 9th sub-frames, or 2nd to
9th sub-frames, or 1st to 4th sub-frames and 6th to
9th sub-frames of the frame.

[0185] Excursus 6: the pilot addition method according to excursus 5,
wherein the determining determines insertion positions of pilots of two
different antennas in each of the resource blocks.

[0186] Excursus 7: the pilot addition method according to excursus 6,
wherein the determining determines the insertion positions of the pilots
of the two antennas in each of the resource blocks such that pilots added
to resource blocks with the same serial number in adjacent sub-frames are
for different antennas.

[0187] Excursus 8: the pilot addition method according to excursus 6,
wherein the determining determines the insertion positions of the pilots
of the two antennas in each of the resource blocks such that pilots added
to resource blocks with adjacent serial numbers in the same sub-frame are
for different antennas.

[0188] Excursus 9: the pilot addition method according to excursus 4,
wherein the judging determines inserting the pilot required by the
subscriber of the new system into each of resource blocks in a 2nd
sub-frame, a 3rd sub-frame, a 7th sub-frame and an 8th
sub-frame of the frame.

[0189] Excursus 10: the pilot addition method according to excursus 9,
wherein the determining determines insertion positions of pilots of four
different antennas in each of the resource blocks.

[0190] Excursus 11: the pilot addition method according to excursus 9,
wherein the determining determines the insertion positions of the pilots
of the four antennas in each of the resource blocks such that pilots
added to resource blocks with the same serial number in adjacent
sub-frames are for different antennas.

[0191] Excursus 12: the pilot addition method according to excursus 9,
wherein the determining determines the insertion positions of the pilots
of the four antennas in each of the resource blocks such that pilots
added to resource blocks with adjacent serial numbers in the same
sub-frame are for different antennas.

[0192] Excursus 13: the pilot addition method according to excursus 4,
wherein the judging determines inserting the pilot required by the
subscriber of the new system into each of resource blocks in any one or
two of a 2nd sub-frame, a 3rd sub-frame, a 7th sub-frame
and an 8th sub-frame of the frame.

[0193] Excursus 14: the pilot addition method according to excursus 13,
wherein the determining determines insertion positions of pilots of eight
different antennas in each of the resource blocks.

[0194] Excursus 15: the pilot addition method according to excursus 14,
wherein the judging determines inserting the pilot required by the
subscriber of the new system into each of the resource blocks of any two
of the 2nd, 3rd, 7th and 8th sub-frames of the frame,
the pilot is inserted into positions of sub-carrier symbol blocks
determined by symbols with serial numbers 9 and 10 in sub-carriers with
serial numbers 1, 4, 7 and 10 in the resource block.

[0195] Excursus 16: a pilot addition apparatus used in a transmitter for
transmitting data to subscriber of an old system and subscriber of a new
system serving as an updated system of the old system, including:

[0196] a new system pilot addition judgment unit configured to judge
whether or not to insert a pilot required by the subscriber of the new
system into a current resource block;

[0197] an insertion position determination unit configured to determine a
sub-carrier symbol block serving as an insertion position of the pilot
required by the subscriber of the new system, from one or more
sub-carrier symbol blocks having a large influence on the statistical
performance for a channel estimation of the subscriber of the old system;
and

[0198] an insertion unit configured to insert the pilot required by the
subscriber of the new system into the sub-carrier symbol block serving as
the insertion position of the pilot required by the subscriber of the new
system determined by the insertion position determination unit.

[0199] Excursus 17: the pilot addition method according to excursus 16,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system according to sectors.

[0200] Excursus 18: the pilot addition method according to excursus 17,
wherein in case a pilot of an antenna of the new system is located at a
sub-carrier having a serial number k in a certain source block in the
first sector, a sub-carrier for the pilot of the antenna in corresponding
source block in the second sector has a serial number of k+1 modulo k,
and a sub-carrier for the pilot of the antenna in corresponding source
block in the third sector has a serial number of k+2 modulo k, k is a
nonnegative integer.

[0201] Excursus 19: the pilot addition method according to excursus 16,
wherein the old system is an LTE system and the new system is an LTE-A
system.

[0202] Excursus 20: the pilot addition method according to excursus 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in 0th to 3rd sub-frames, 6th to 9th
sub-frames, or 2nd to 9th sub-frames, or 1st to 4th
sub-frames and 6th to 9th sub-frames of the frame.

[0203] Excursus 21: the pilot addition method according to excursus 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in a 2nd sub-frame, a 3rd sub-frame, a 7th
sub-frame and an 8th sub-frame of the frame.

[0204] Excursus 22: the pilot addition method according to excursus 19,
wherein the new system pilot addition judgment unit determines inserting
the pilot required by the subscriber of the new system into each of
resource blocks in any one or two of a 2nd sub-frame, a 3rd
sub-frame, a 7th sub-frame and an 8th sub-frame of the frame.

[0205] Excursus 23: the pilot addition method according to excursus 19,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system in each of the resource blocks such that pilots added to resource
blocks with the same serial number in adjacent sub-frames are for
different antennas.

[0206] Excursus 24: the pilot addition method according to excursus 19,
wherein the insertion position determination unit determines the
insertion position of the pilot required by the subscriber of the new
system in each of the resource blocks such that pilots added to resource
blocks with adjacent serial numbers in the same sub-frames are for
different antennas.

[0208] a first channel model channel estimation error statistical
determination unit configured to determine a statistical distribution of
channel estimation errors of an old system subscriber under a first
channel model;

[0209] a second channel model channel estimation error statistical
determination unit configured to determine a statistical distribution of
channel estimation errors of an old system subscriber under a second
channel model; and

[0210] a new system antenna pilot position determination unit configured
to determine insertion positions of pilots of antennas of a new system in
a sub-frame or RB, according to determination results of the first
channel model channel estimation error statistical determination unit and
the second channel model channel estimation error statistical
determination unit.

[0212] determining a statistical distribution of channel estimation errors
of an old system subscriber under a first channel model;

[0213] determining a statistical distribution of channel estimation errors
of an old system subscriber under a second channel model; and

[0214] determining insertion positions of pilots of antennas of a new
system in a sub-frame or RB, according to determination results of the
above two determining.

[0215] Features described and/or illustrated with respect to one
embodiment can be used in one or more other embodiments in a same or
similar way, and/or combine with or replace features in other
embodiments.

[0216] To be noted, the term "include/comprise" or "including/comprising"
herein refers to existence of feature, component, step or assembly, not
excluding existence or addition of one or more other features,
components, steps, assemblies or a combination thereof.

[0217] In addition, the method of the present invention is not limited to
be executed according to the time order as described herein, and can be
executed in other time sequentially, concurrently or independently. Thus,
the execution order of the method as described herein does not limit the
technical scope of the present invention.